The purpose of the proposed research is to investigate the interactions that take place on the tooth surface and which lead to the formation of the aquired enamel pellicle. This thin film of selectively adsorbed salivary proteins covers the dental enamel surface and contains the sites to which cariogenic organisms become attached. It therefore plays an important role in the initial stages of the formation of dental plaque, and becomes interposed between the plaque and the underlying enamel. Since it acts as a diffusion barrier, it affects both the intensity of carious attack and the rate of loss of the products of demineralization. The research objectives are to identify the salivary protein precursors of the pellicle, to study its mechanism of formation and to identify the active sites to which bacteria become attached.